Abstract

Ionizing shock waves in helium and argon are structured by nonequilibrium radiative and inelastic collisional transitions. The model atom of the monatomic gas has three electronic energy levels. The monatomic gas is not in local equilibrium with respect to population, and local translational equilibrium between the heavy species present and the electron gas is not assumed either. For the flow conditions studied, the physics and morphology of the shock is further developed on a continuum basis from previous work, and the shock is found to consist of a far precursor due to radiative excitation, a near precursor due to radiative ionization, an embedded transport shock, an inelastic and thermal collisional relaxation zone, and an equilibrium radiating tail. Of particular interest in the results are (i) the heating of the electron gas in the precursor by the said radiative and the associated de‐exciting collisional mechanisms and (ii) the subsequent, electron‐triggered collisional relaxation zone which is optically transparent to radiation; thus, nonequilibrium radiative and collisional processes are locally uncoupled throughout the shock. A family of numerical examples is displayed diagrammatically for an upstream temperature of 300°K and an upstream pressure of 10−4. atm. Selected were those accompanying downstream temperatures giving nominal equilibrium degrees of ionization of either 0.8 or 0.95.